If you type /italics/, the forum software will render it as
italics
. If you type an un-escaped forward slash right in front of a word,
the forum software may think that it marks the beginning of a long paragraph of italic text, when in fact it isn't.

There are other special formatting characters like this, listed on the posting page. If you want to include one of them as plain text in your message, you may need to put a backslash (\) in front of it, e.g., \/ for /, \* for *, etc.

/ (italics) and * (boldface) are the ones that seem to trip up the most people.